<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <div id="l1">
        123
    </div>
    <script type="text/javascript">
        var i= document.getElementById("l1"); //找
        i.innerText="456";    //改
    </script>
</body>
</html>